The present invention relates to a fuel tank unit or device of a motorcycle having a structure in which a fuel pump is arranged in an interior of a fuel tank body.
Recently, it is required for, so-called, a two-wheeled motorcycle to discharge an exhaust gas containing low harmful component for environment and to be operated with improved fuel economy, and in accordance with such requirement, there has been developed a fuel supply system utilizing a fuel injection unit. In such motorcycle, it is necessary to feed, under pressure, the fuel in the fuel tank into the fuel injection unit disposed on the engine side, and therefore, a fuel pump is mounted to the fuel tank.
FIG. 4 shows a conventional fuel tank unit of the type mentioned above.
With reference to FIG. 4, the fuel tank unit includes a tank body 101 having an inner bottom surface 101a, and a fuel pump 102 is mounted in the vicinity of the lowest portion of the inner bottom surface 101a. The fuel pump 102 is provided with a suction unit or member (fuel intake port) 103 is located to a position slightly higher than the bottom surface 101a in an installed (viewed) state. When the fuel pump 102 is driven, the fuel in the tank body 101 is sucked through the suction unit 103 so as to provide a predetermined pressure and the pressurized fuel is fed to the fuel injection unit 105 through a fuel hose 104.
However, according to the structure of the conventional fuel tank unit mentioned above, since the fuel intake port (suction unit) 103 is disposed to the position higher than the bottom surface 101a of the tank body 101, for example, at a time when the motorcycle is rapidly reduced in running speed in a case of less remaining fuel in the fuel tank body 101, the fuel in the tank body 101 moves forward therein and the fuel suction unit 103 is exposed above the surface of the fuel in the tank body 101. In such case, the fuel pump 102 sucks air and, hence, there causes a temporary fuel running-out, thus being inconvenient.
An object of the present invention is to substantially eliminate inconvenience encountered in the prior art mentioned above and to provide a fuel tank unit of a motorcycle capable of preventing a temporary fuel running-out at the time when a less amount of fuel remains in the tank and improving a sealing performance between the tank body and the fuel pump with reduced parts and members associated with the fuel pump.
This and other objects can be achieved according to the present invention by providing a fuel tank unit of a motorcycle comprising:
a tank body having a bottom portion to which a through hole is formed in a standing state of the motorcycle;
a fuel pump mounted to the bottom portion of the tank body;
a pump case having a bottomed bawl-shape mounted to the fuel pump to be liquid-tightly to the through hole formed to the tank body so as to communicate an inner space of the pump case with an inner space of the tank body through the through hole; and
a suction unit for the fuel pump disposed in the pump case at a height level between the bottom portion of the tank body and a bottom surface of the pump case.
At a time when the remaining fuel amount is small, even if the motorcycle is rapidly reduced in speed and the fuel in the tank body is one-sided to its forward position, the liquid surface of the fuel remaining in the pump case is kept above the location level of the suction unit, thus preventing a temporary fuel running-out from occurring.
In a preferred example of the present invention, a cylindrical member is disposed to the bottom portion of the tank body so as to extend upward to surround an outer periphery of the through hole.
Furthermore, the fuel tank unit of the present invention may further comprises a pump mount bracket mounted to the bottom portion of the tank body to be liquid-tightly and formed with a pump mount hole to which the fuel pump is mounted and the pump case is mounted to the pump mount hole so that a lower surface portion of the pump mount bracket and an upper surface portion of the pump case are mated with each other liquid-tightly and then fastened together. In this example, the cylindrical member is disposed to the pump mount bracket so as to extend upward to surround an outer periphery of the pump mount hole. The cylindrical member is formed integrally with the pump mount bracket.
According to such preferred example, the location of the cylindrical surrounding member makes further high the surface level of the fuel remaining in the fuel pump with respect to the suction unit at the time when the fuel is moved in the tank body to be one-sided to the forward position therein to thereby further surely prevent the fuel running out from occurring.
The location of the pump mount bracket makes it possible to improve the assembling performance and sealing performance between the tank body and the fuel pump. The number of members or parts can be reduced by integrally forming the cylindrical member to this pump mount bracket.
The nature and further characteristic features of the present invention can be made more clear from the following descriptions made with reference to the accompanying drawings.